#include<stdio.h>
#include<unistd.h>

int g_val=100;

int main(void)
{
    pid_t id=fork();
    if(id==0)
    {
        int cnt=0;
        while(1)
        {
            printf("I am child  , pid:%d, ppid:%d, g_val:%d, &g_val:%p\n",
                    getpid(),getppid(),g_val,&g_val);
            sleep(1);
            cnt++;
            if(cnt==5)
            {
                g_val=200;
                printf("child changed g_val : 100->200 success\n");
            }
        }
    }
    else 
    {
        while(1)
        {

            printf("I am parent , pid:%d, ppid:%d, g_val:%d, &g_val:%p\n",
                    getpid(),getppid(),g_val,&g_val);
            sleep(1);
        }
    }

    return 0;

}
